C# Antipatterns

Answer 1

Throwing NullReferenceException:

if (FooLicenceKeyHolder == null)
    throw new NullReferenceException();

Answer 2

This is true I seen it with my own eyes.

public object GetNull()
{
     return null;
}

It was actually used in the app, and even had a stored procedure to go with it too, an sp_GetNull that would return null....

that made my day.

I think the sp was used for a classic asp site .. something to do with a result set. the .net one was someone idea of "converting" the code into .net...

Answer 3

Rethrowing the exception incorrectly. To rethrow an exception :

try
{
    // do some stuff here
}
catch (Exception ex)
{
    throw ex;  // INCORRECT
    throw;     // CORRECT
    throw new Exception("There was an error"); // INCORRECT
    throw new Exception("There was an error", ex); // CORRECT
}

Answer 4

object variable;
variable.close(); //Old code, use IDisposable if available.
variable.Dispose(); //Same as close.  Avoid if possible use the using() { } pattern.
variable = null; //1. in release optimised away.  2. C# is GC so this doesn't do what was intended anyway.

Answer 5

Using properties for anything other than to simply retrieve a value or possibly an inexpensive calculation. If you are accessing a database from your property, you should change it to a method call. Developers expect that method calls might be costly, they don't expect this from properties.

Answer 6

int foo = 100;
int bar = int.Parse(foo.ToString());

Or the more general case:

object foo = 100;
int bar = int.Parse(foo.ToString());